This invention relates to a dampening water or fountain solution composition, and more particularly to a dampening water composition not containing the isopropyl alcohol universally used in the prior art wherein the tinting and scumming of the printed matter and various other difficulties do not arise.
Heretofore, various printing processes have been widespread. Of these processes, the most widely used process is the lithographic printing (offset) process.
In this lithographic printing process, there is used a machine plate wherein a lipophilic printing area on which a printing ink composition deposits and a hydrophilic non-image area on which the printing ink composition does not deposit are formed on the surfaces of materials such as presensitized aluminum plates by a photomechanical process. This machine plate is wound around the plate cylinder of a printing machine and brought into contact with an ink roller to feed the printing ink composition from the ink roller to the machine plate. A solution called a dampening water has been previously applied to the machine plate so that the ink composition deposits only on the printing area without depositing on the non-image area. This solution is present on the non-image area in the form of a uniformly thin water film. This film of dampening water inhibits the deposition of the ink composition on the non-image area.
It is required that such a dampening water has a proper surface tension and therefore an aqueous solution of isopropyl alcohol having a concentration of from 5% to 20% by weight has heretofore been used.
However, this isopropyl alcohol has been regulated by a revision of labor safety so that the concentration of isopropyl alcohol in an aqueous solution must be less than 5% by weight. There is a high probability that isopropyl alcohol must be used at the lower concentration in the future. If the concentration of isopropyl alcohol in the dampening water composition is less than 5% by weight, the performance of the dampening water composition will be insufficient and satisfactory printed matter cannot be obtained. Further, substantially all of the dampening water composition eventually evaporates in the air. including its isopropyl alcohol, so the hazardous nature of isopropyl alcohol poses various problems such as working environment contamination as well as exterior environment contamination.
It is therefore an object of the present invention to provide a dampening water composition capable of giving a high quality printed matter without contamination working environment as well as exterior environment with isopropyl alcohol.